1. Field of the Invention
The present invention relates to a process for enabling gel covering seed or seeded gel culture media to be preserved so as to make them sprout at a large percentage, and for reducing the cost in transfer thereof by reducing the volume of seed covered with gel or of gel media.
2. Related Art
Generally, seed of vegetable or flower (they will be simply called seed hereafter) are sown directly onto a farm, a garden and the like, or are sown in a nursery for initial growth and subsequently transplanted to a farm, a garden and the like. However, directly sown seed are liable to suffer blight through soil. Also, if they are minute, they are liable to be carried away by rainwater or sprinkled water. Furthermore, they are liable to be eaten by birds, animals, vermin and the like, because they are near the ground surface.
For prevention against blight, which is one of the above mentioned harms, there are such well-known conventional methods as to soak seed in chemical composition fluid, to stick chemical composition powder to surfaces of seed, and to dry seed by heating, for example. However, in adopting the first method, it so occasionally happens that the medicine cannot permeate the soaked seed fully. The cloth of chemical composition covering seed, which is formed by the second method, peels off easily. Thus, the two methods are not satisfying for the prevention. The last method of the above has a problem in application thereof because the seeds may have been heat-denatured. If the application is erred, the seed dies.
For prevention against carrying away and eating by animals, a surface of a seed is covered with coating so as to enlarge the particle of the seed. Coating of seed enables seed sowing by machine or manual operation to be easy and accurate. Furthermore, it has such an advantage that chemical compositions like a germicide, a vermicide, a medicine for avoiding animals, a chemical composition for promoting nutrition (a fertilizer) and so on can be added to the coating. Accordingly, many studies and propositions about coating of seed have been made in recent years.
However, it is complicated to stick a coating to a seed is complicated because it requires so many processes that the surface of the seed is sprayed with dilute binder solution in water and the seed is revolved on chemical composition powder so as to be coated with the chemical composition powder. Furthermore, if seeds are small, they stick to each other, so that it is difficult in making particles of seed dividually.
Then, a technique of using aqueous gel for coating, as described in the Japanese Patent Publication Hei. 5-63122, for example, comes to be proposed. In the technique, water required for germination is contained within gel, and a seed is covered directly with oxygen, required for germination when it is coated. Furthermore, an apparatus for covering seed with gel, which is described in the above cited document, can coat plane or minute seed besides spherical seed.
The above said method of covering seed with gel will be explained. A seed and air supplying pipe (a plunger) is inserted into a nozzle, an annular gel flowing hole is formed between the inner side of the nozzle and the outer side of the end portion of the seed and air supplying pipe. When gel flows out from the gel flowing hole, a membrane of gel including air is formed at the bottom opening of the gel flowing hole. Then, a seed is dropped into the seed and air supplying pipe, thereby the seed is included together with the air in the membrane of gel, so that a gel including the seed and the air falls by the weight of itself of compression. The falling gel including the seed and the air comes to be substantially spherical by the surface tension thereof and falls into a hardener. The gel is soaked in the hardener for a predetermined time, so as to be hardened. Then, it is transferred into a washing water tank, so that the sticking hardener is washed off.
The seed covered with gel by such a manner are substantially of a size, so that they can be sown by a seeding machine. However, when they are left at room temperature, they germinate in a few days, so that a period of sowing by machine is restricted.
Then, as described in the Japanese Patent Publication Hei. 7-14286, they are dried and reserved until a period of sowing. When the period has come, they are supplied with water so as to be changed back into their original spherical shapes, so that they can be sown by a seeding machine. However, all the sown seed cannot germinate, because some seed are injured in processes of harvest, transferring, freeze-drying and the like, some are originally defective, and some are dead. The existence of such seed requires sowing extra, thinning and transplanting, thereby making complicated.
One object of the present invention is to provide a processing of seed covered with gel so that they can sprout at further high rate, can suffer a long-term reservation and are light enough to be carried easily.
On the other hand, some seed of vegetable or flower are cultured by gel culture media so as to prevent them from dead and delay of growth at their early vegetative periods. The Japanese Utility Model Publication Sho. 61-24017 and the Japanese Patent Laid Open Gazette Sho. 63-71108, for example, describe such a technique that gel is used for a culture medium.
According to the technique of the former cited document, a seed is covered with a cylindrical or square pillar-like shaped aqueous gel, and a hole toward the seed is bored within the gel before or after covering. The gel is supplied with water, so that it is enlarged to be between twice and a thousand times as large as the original. The seed germinates by getting water and nutritive substance from the gel, grows to the requested degree by getting oxygen of the outside through the hole, and is transplanted.
According to the technique of the latter cited document, a sheet of culture medium is made of gel. The sheet of culture medium (the gel sheet) is dried to be hardened. A seed is fixed onto the gel sheet. The gel sheet is supplied with water, so that the seed germinates. When the initiated seed grows to be a seedling of the requested growth, the gel sheet is cut into the predetermined size, and the seedling is transplanted together with the cut gel sheet.
The gel culture media used in the both techniques are small and light enough to be transferred and reserved easily. The seeded gel culture media are enlarged by supplying of water for germination. However, all the seed cannot germinate, because some seed are injured in processes of harvest, transferring and the like, some are originally defective, and some are dead. Furthermore, in case of the former technique, it so occasionally happens that a seed covered with gel is killed by excessive drying or a seed is injured by boring a hole. Also, in case of the latter technique, it so occasionally happens that even if a seed germinates, it cannot take its roots into the gel culture medium but along the surface thereof because of ease of their extension, thereby the germule withers. Furthermore, even if the seed takes its roots into the gel culture medium, it occasionally withers because of shortage of oxygen.
Thus, all the seed involve some seed which cannot germinate and some which wither in spite of germination, thereby it is necessary to seed extra. As a result, seedlings cannot be obtained more than the certain quantity.
The other object of the present invention is to provide a processing of a seeded gel culture medium so that the seed can sprout at further high rate, can suffer a long-term reservation and the seeded gel culture medium are light enough to be carried easily.